An Ultra-High Time Resolution Cosmic-Ray Detection Mode for the Murchison Widefield Array

The radio-wavelength detection of extensive air showers (EASs) initiated by cosmic-ray interactions in the Earth's atmosphere is a promising technique for investigating the origin of these particles and the physics of their interactions. The Low-frequency Array (LOFAR) and the Owens Valley Long Wavelength Array (OVRO-LWA) have both demonstrated that the dense cores of low-frequency radio telescope arrays yield detailed information on the radiation ground pattern, which can be used to reconstruct key EAS properties and infer the primary cosmic-ray composition. Here, we demonstrate a new observation mode of the Murchison Widefield Array (MWA), tailored to the observation of the sub-microsecond coherent bursts of radiation produced by EAS. We first show how an aggregate 30.72MHz bandwidth (3072×10kHz frequency channels) recorded at 0.1ms resolution with the MWA's voltage capture system (VCS) can be synthesized back to the full bandwidth Nyquist resolution of 16.3ns. This process, which involves "inverting"two sets of polyphase filterbanks, retains 90.5% of the signal-to-noise of a cosmic-ray signal. We then demonstrate the timing and positional accuracy of this mode by resolving the location of a calibrator pulse to within 5m. Finally, preliminary observations show that the rate of nanosecond radio-frequency interference (RFI) events is 0.1Hz, much lower than that found at the sites of other radio telescopes that study cosmic rays. We conclude that the identification of cosmic rays at the MWA, and hence with the low-frequency component of the Square Kilometre Array, is feasible with minimal loss of efficiency due to RFI

Support services for victims and survivors of child sexual abuse

Some of the content in this report may be distressing to readers.Aims The four broad research aims were to: ● understand more about victims and survivors’ reasons for not accessing support services and any barriers to access; ● learn about victims and survivors’ perceptions and experiences of support services; ● understand what support services victims and survivors think are available to them and how to access them; and ● explore whether there are unmet needs for support services which impact on whether victims and survivors access support. Methods The sample was drawn from 634 adults who self-identified as victims and survivors of child sexual abuse as part of the ‘Abuse during childhood’ module in the Crime Survey for England and Wales (CSEW) year ending March 2019 (Office for National Statistics, 2020).3 A mixed-methods approach was used to explore the above research aims: ● A quantitative online survey4 of 181 victims and survivors from the CSEW recontact sample, including both those who had and had not accessed support. Descriptive and inferential analyses were conducted. ● Twenty-four qualitative in-depth interviews with three groups: (A) eight who had not accessed support services; (B) eight who self-identified as having had positive experiences of support services; and (C) eight who had negative experiences of support services. The interviews were analysed using thematic analysis. These were supplemented with six pen portraits (two from each of the above groups), and a network map to aid understanding of the service landscape. The research participants The ages of the survey respondents ranged from 19 to 74 years, with an average of 47 years. Around four in five identified as female (82%), the majority identified as being of a White ethnic background (92%), and one in three reported having a disability (33%). All regions of England and Wales were represented, with one in four living in London or South East England (26%). Nearly nine in ten identified as heterosexual (89%) Respondents reported experiencing between one and eight types of child sexual abuse. The two most common forms were being kissed or groped on any part of the body in a sexual way (73%) and penetration (64%). The age at first victimisation spanned from infancy to 17 years old, with an average of 9 years old. Child sexual abuse was more likely to have occurred in a familial setting (41%) than an institutional one (11%). Two in five (43%) respondents identified a friend, acquaintance or neighbour as the perpetrator. Around one in four (27%) identified an immediate – typically male – family member as the perpetrator. A stranger was identified by one in five (20%) respondents. Just over one in five respondents had never previously disclosed their experiences of child sexual abuse (21%), while four in five had made a disclosure (79%). Respondents were more than twice as likely to report making a disclosure later in life (75%) than at the time of the abuse (28%). A quarter disclosed at both points (24%)

Long-period Radio Pulsars: Population Study in the Neutron Star and White Dwarf Rotating Dipole Scenarios

© 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/The nature of two recently discovered radio emitters with unusually long periods of 18min (GLEAM-X J1627-52) and 21min (GPM J1839-10) is highly debated. Their bright radio emission resembles that of radio magnetars, but their long periodicities and lack of detection at other wavelengths challenge the neutron-star interpretation. In contrast, long rotational periods are common in white dwarfs but, although predicted, dipolar radio emission from isolated magnetic white dwarfs has never been unambiguously observed. In this work, we investigate these long-period objects as potential isolated neutron-star or white-dwarf dipolar radio emitters and find that both scenarios pose significant challenges to our understanding of radio emission via pair production in dipolar magnetospheres. We also perform population-synthesis simulations based on dipolar spin-down in both pictures, assuming different initial-period distributions, masses, radii, beaming fractions, and magnetic-field prescriptions, to assess their impact on the ultra-long pulsar population. In the neutron-star scenario, we do not expect a large number of ultra-long period pulsars under any physically motivated (or even extreme) assumptions for the period evolution. On the other hand, in the white-dwarf scenario, we can easily accommodate a large population of long-period radio emitters. However, no mechanism can easily explain the production of such bright coherent radio emission in either scenarios.Peer reviewe

A long-period radio transient active for three decades: population study in the neutron star and white dwarf rotating dipole scenarios

The nature of two recently discovered radio emitters with unusually long periods of 18min (GLEAM-X J1627-52) and 21min (GPM J1839-10) is highly debated. Their bright radio emission resembles that of radio magnetars, but their long periodicities and lack of detection at other wavelengths challenge the neutron-star interpretation. In contrast, long rotational periods are common in white dwarfs but, although predicted, dipolar radio emission from isolated magnetic white dwarfs has never been unambiguously observed. In this work, we investigate these long-period objects as potential isolated neutron-star or white-dwarf dipolar radio emitters and find that both scenarios pose significant challenges to our understanding of radio emission via pair production in dipolar magnetospheres. We also perform population-synthesis simulations based on dipolar spin-down in both pictures, assuming different initial-period distributions, masses, radii, beaming fractions, and magnetic-field prescriptions, to assess their impact on the ultra-long pulsar population. In the neutron-star scenario, we cannot reproduce the large number of expected ultra-long period pulsars under any physically motivated (or even extreme) assumptions. Thus, if GLEAM-X J1627-52 and GPM J1839-10 are confirmed as neutron-star pulsars (even if they are magnetars), this would necessarily call for a significant revision of our understanding of birth parameters at the population level. On the other hand, in the white-dwarf scenario, no mechanism can explain the production of such a bright coherent radio emission in isolated magnetic white dwarf systems (binaries with low mass companions are still viable), although we can easily accommodate a large population of long-period radio emitters.Comment: 8 pages, 4 figures; ApJ Letters submitte

Simultaneous observations of giant pulses from the Crab pulsar, with the Murchison Widefield Array and Parkes radio telescope: implications for the giant pulse emission mechanism

We report on observations of giant pulses from the Crab pulsar performed simultaneously with the Parkes radio telescope and the incoherent combination of the Murchison Widefield Array (MWA) antenna tiles. The observations were performed over a duration of approximately one hour at a center frequency of 1382 MHz with 340 MHz bandwidth at Parkes, and at a center frequency of 193 MHz with 15 MHz bandwidth at the MWA. Our analysis has led to the detection of 55 giant pulses at the MWA and 2075 at Parkes above a threshold of 3.5σ and 6.5σ, respectively. We detected 51% of the MWA giant pulses at the Parkes radio telescope, with spectral indices in the range of-3.6 > α > -4.9 (Sv μ ∝ Va). We present a Monte Carlo analysis supporting the conjecture that the giant pulse emission in the Crab is intrinsically broadband, the less than 100% correlation being due to the relative sensitivities of the two instruments and the width of the spectral index distribution. Our observations are consistent with the hypothesis that the spectral index of giant pulses is drawn from normal distribution of standard deviation 0.6, but with a mean that displays an evolution with frequency from −3.00 at 1382 MHz, to −2.85 at 192 MHz

Simultaneous observations of giant pulses from the Crab pulsar, with the Murchison Widefield Array and Parkes radio telescope: implications for the giant pulse emission mechanism

We report on observations of giant pulses from the Crab pulsar performed simultaneously with the Parkes radio telescope and the incoherent combination of the Murchison Widefield Array (MWA) antenna tiles. The observations were performed over a duration of approximately one hour at a center frequency of 1382 MHz with 340 MHz bandwidth at Parkes, and at a center frequency of 193 MHz with 15 MHz bandwidth at the MWA. Our analysis has led to the detection of 55 giant pulses at the MWA and 2075 at Parkes above a threshold of 3.5σ and 6.5σ, respectively. We detected 51% of the MWA giant pulses at the Parkes radio telescope, with spectral indices in the range of-3.6 > α > -4.9 (Sv μ ∝ Va). We present a Monte Carlo analysis supporting the conjecture that the giant pulse emission in the Crab is intrinsically broadband, the less than 100% correlation being due to the relative sensitivities of the two instruments and the width of the spectral index distribution. Our observations are consistent with the hypothesis that the spectral index of giant pulses is drawn from normal distribution of standard deviation 0.6, but with a mean that displays an evolution with frequency from −3.00 at 1382 MHz, to −2.85 at 192 MHz

Within- and between-person and group variance in behavior and beliefs in cross-cultural longitudinal data

This study grapples with what it means to be part of a cultural group, from a statistical modeling perspective. The method we present compares within- and between-cultural group variability, in behaviors in families. We demonstrate the method using a cross-cultural study of adolescent development and parenting, involving three biennial waves of longitudinal data from 1296 eight-year-olds and their parents (multiple cultures in nine countries). Family members completed surveys about parental negativity and positivity, child academic and social-emotional adjustment, and attitudes about parenting and adolescent behavior. Variance estimates were computed at the cultural group, person, and within-person level using multilevel models. Of the longitudinally consistent variance, most was within and not between cultural groups—although there was a wide range of between-group differences. This approach to quantifying cultural group variability may prove valuable when applied to quantitative studies of acculturation

The genetic history of the Southern Arc: a bridge between West Asia and Europe

By sequencing 727 ancient individuals from the Southern Arc (Anatolia and its neighbors in Southeastern Europe and West Asia) over 10,000 years, we contextualize its Chalcolithic period and Bronze Age (about 5000 to 1000 BCE), when extensive gene flow entangled it with the Eurasian steppe. Two streams of migration transmitted Caucasus and Anatolian/Levantine ancestry northward, and the Yamnaya pastoralists, formed on the steppe, then spread southward into the Balkans and across the Caucasus into Armenia, where they left numerous patrilineal descendants. Anatolia was transformed by intra–West Asian gene flow, with negligible impact of the later Yamnaya migrations. This contrasts with all other regions where Indo-European languages were spoken, suggesting that the homeland of the Indo-Anatolian language family was in West Asia, with only secondary dispersals of non-Anatolian Indo-Europeans from the steppe

The sound of tablets during coating erosion, disintegration, deaggregation and dissolution

This research aims to address a gap in our understanding of the mechanisms by which pharmaceutical tablets achieve highly reproducible and predictable drug release. The present industrial and regulatory practice is centred around tablet dissolution, i.e. what follows disintegration, yet the vast majority of problems that are found in formulation dissolution testing can be traced back to the erratic disintegration behaviour of the medicinal product. It is only due to the distinct lack of quantitative measurement techniques for disintegration analysis that this situation arises. Current methods involve costly, and time-consuming test equipment, resulting in a need for more simple, green and efficient methods which have the potential to enable rapid development and to accelerate routine solid drug formulation dissolution and disintegration testing. In this study, we present a novel approach to track several sequential tablet dissolution processes, including coating erosion, disintegration, deaggregation and dissolution using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS). BARDS, in combination with minimal usage of UV spectroscopy, can effectively track these processes. The data also show that a solid oral dose formulation has an intrinsic acoustic signature which is specific to the method of manufacture and excipient composition

Discovery of a steep-spectrum low-luminosity pulsar with the Murchison Widefield Array

We report the discovery of the first new pulsar with the Murchison Widefield Array (MWA), PSR J0036−1033, a long-period (0.9 s) nonrecycled pulsar with a dispersion measure (DM) of 23.1 pc cm−3 . It was found after processing only a small fraction (∼1%) of data from an ongoing all-sky pulsar survey. Follow-up observations have been made with the MWA, the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Parkes 64 m telescopes, spanning a frequency range from ∼150 MHz to 4 GHz. The pulsar is faint, with an estimated flux density (S) of ∼1 mJy at 400 MHz and a spectrum S(v) α v - S 2.0±0.2, where ν is frequency. The DM-derived distance implies that it is also a low-luminosity source (∼0.1 mJy kpc2 at 1400 MHz). The analysis of archival MWA observations reveals that the pulsar’s mean flux density varies by up to a factor of ∼5–6 on timescales of several weeks to months. By combining MWA and uGMRT data, the pulsar position was determined to arcsecond precision. We also report on polarization properties detected in the MWA and Parkes bands. The pulsar’s nondetection in previous pulsar and continuum imaging surveys, the observed high variability, and its detection in a small fraction of the survey data searched to date, all hint at a larger population of pulsars that await discovery in the southern hemisphere, with the MWA and the future low-frequency Square Kilometre Array